There are many applications for optical spatial light modulators of high intensity optical beams. Particularly in commercial printing applications, optical laser bars with output power .gtoreq.20 W range are not uncommon. If these laser bars are used in a continuous wave mode (CW) as a source of high power light, a means to modulate the high intensity beams of light into a high number of separate pixels is required. Such high power laser bars have wavelengths usually in the 0.8 .mu.m to 1 .mu.m range.
U.S. Pat. No. 4,281,904 discloses the use of a total internal reflection (TIR) modulator to modulate a visible He-Ne laser beam. In U.S. Pat. No. 4,281,904, a stop is principally used in the output optics to block the zero order beam and the diffracted first order light is imaged to the media to get modulation contrasts of 100 to 1 for low overall visible light levels. The voltage applied in the arrangement of U.S. Pat. No. 4,281,904 corresponds to the amount of index change necessary in a crystal to diffract incident light into the first order beam efficiently. That diffraction from the fundamental to the first order mode gives a large 20 dB contrast. Unfortunately with this arrangement, light is thrown away (i.e. the un-diffracted percentage and higher orders), and there are nulls (no light refracted) in the optical image. Other patents such as U.S. Pat. No. 4,673,953 use complex schemes to produce `null free` devices. These complex schemes involve the use of extra optics to remove nulls.